Thursday, October 28, 2010

Where Is Water on Moon From--Volcanoes, Sun ... Earth?

For many, 2009 will be remembered as the year water on the moon was confirmed beyond any reasonable doubt.

"You're seeing the culmination of a whole bunch of missions that were instrumented specifically to address this question," said Paul Spudis of the NASA-funded Lunar and Planetary Institute (LPI) in Houston, Texas.

"Was it deposited in a single big event that was recent? Or is this stuff that has been around for billions of years?" said Peter Schultz, an LCROSS scientist at Brown University in Rhode Island. "We don't know."

Right now there are three major scientific theories of how the moon got its water—and a "wildly speculative" fourth idea that can't be ruled out just yet.

THEORY ONEAncient Volcanoes Pushed Moon's Water to Surface

The moon's water was there from the start, one theory goes—water was an ingredient in the moon's creation, as it was for Earth's.

Lunar water could be home-brewed, with some help from the sun, some scientists speculate.

The sun constantly emits a stream of particles called solar wind. Positively charged hydrogen ions, or protons, in the solar wind may strike the moon and interact with oxygen-rich minerals in lunar soil to form H2O, aka water, according to this theory.

Forming water via solar wind would be a slow process, Brown University's Schultz said. But "even if you're only accumulating a molecule [of water] a day this way, over billions of years you can do a lot of things."